Multiple Choice
Which of the following represents the correct ground-state electron configuration for silicon (Si)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for the element phosphorus (atomic number 15)?
A
1s^2 2s^2 2p^6 3s^2 3p^6
B
1s^2 2s^2 2p^6 3s^2 3p^5
C
1s^2 2s^2 2p^6 3s^2 3p^1
D
1s^2 2s^2 2p^6 3s^2 3p^3
Verified step by step guidance1
Identify the atomic number of phosphorus, which is 15. This means phosphorus has 15 electrons to be placed in its electron configuration.
Recall the order of filling electron orbitals based on the Aufbau principle: 1s, 2s, 2p, 3s, 3p, and so on.
Fill the orbitals with electrons following the maximum capacity of each: 1s can hold 2 electrons, 2s can hold 2, 2p can hold 6, 3s can hold 2, and 3p can hold 6.
Add electrons in order until you reach 15 total electrons: 2 in 1s, 2 in 2s, 6 in 2p, 2 in 3s, and the remaining 3 in 3p.
Write the electron configuration as $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{3}$, which correctly represents the distribution of 15 electrons in phosphorus.
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